My monitor has stopped working light pulses but no display. Computer is OK.

I have an Apple Cinema HD display running from a pc. All Ok yesteday on shut down, but this morning the monitor stays black although the 'on/off' light pulses. Computer is fine with a substitute monitor. Does this mean that the monitor is dead? It's about 6 years old and hasn't has a lot of use so that seems a bit much for an expensive bit of kit!